The Nevada Democrat singled out GOP strategist Karl Rove as an abuser of the system because his tax-exempt group, Crossroads GPS, spent millions on the 2012 election to defeat Democrats. There’s no evidence right now, however, that the IRS probed the bigger and flashier nonprofits like Crossroads GPS.

Currently, nonprofit “social welfare” groups like Crossroads GPS can run ads and send mailers comparing candidates on the issues or discussing a single candidate’s positions, but they’re prevented from advocating for or against a specific candidate. While both groups can raise unlimited funds, unlike super PACs, non-profits aren’t required to disclose their donors.

But Reid argued that Rove’s nonprofit operated with overtly political motives.

“His organization, Rove’s organization, [has] one purpose and one purpose only and that’s to defeat Democrats. Anyone who thinks otherwise is being willfully foolish,” Reid said. “Preventing overtly political groups like the ones run by Karl Rove as masquerading as social welfare organizations, is really a critically important tasks.”

Rove’s group was one that several Democrats singled out in 2010, when they asked the IRS to investigate whether they were violating their tax exempt status. Reid said he didn’t know if those requests were what prompted the eventual IRS overreach.

“I really don’t know, all I know is when you have almost a billion dollars spent on affecting good things socially for the American people, this isn’t one of them,” Reid said.

Reid said the IRS was “inexcusable” for singling out up to 100 conservative groups seeking tax exempt status based on “tea party” or “patriot” being in their names, or those that focused on other conservative buzzwords.

“There is another issue at stake here, and we cannot lose sight of this,” Reid told reporters. “There are these shadowy political groups masquerading as social welfare organizations in order to solicit anonymous donations from we don’t know who, big corporations and ultra-wealthy people. That needs to stop.”

Democrats were quick to join Republicans on Monday in condemning the IRS. President Barack Obama called the allegations “outrageous,” saying if they were true that actions would be taken against those targeting groups.

On Tuesday, Attorney General Eric Holder announced the Justice Department and FBI will conduct a criminal probe into the allegiations.

Reid provided one of the first public defenses for the IRS activities, arguing that there is a legitimate need to investigate those groups that are “masquerading” as social welfare organizations.

Reid acknowledged that politically motivated non-profits are not singularly located on the right side of the political spectrum.

“We do not know exactly how much money was spent in the last election by these groups,” Reid said. “And I acknowledge most of the money was spent on the right wing but there was plenty on the left wing. It’s said to be almost a billion dollars.”